As known for a long time and evident for example from U.S. Pat. No. 6,030,178 or equally from US 2004/165989, especially in the case of rotors for turbines, the individual blades are fastened on a rotor in a ring by the rotor having a multiplicity of recesses on its outer circumference which are arranged axially and parallel next to each other in the circumferential direction and which for example are formed as female configurations of a fir-tree profile. The blades which are to be installed have a blade root which corresponds in shape and is formed as corresponding male configurations of the fir-tree profile in relation to the corresponding female configurations in the rotor. When installing the rotor, the blades are inserted in succession in the axial direction into these recesses of the rotor, and for sealing between the adjacent blades the lower shrouds of the adjacent blades are pushed next to each other in the process. As has been known from WO 03/027445, in this case the fact is to be taken into account that on the hand there must always be the best possible seal between the adjacent shrouds, but that on the other hand the heat-induced expansion of the individual components also has to be taken into consideration.